Start by boing the potatoes in salted water for around 30 minutes.
Once the potatoes are cooked, peel them and mash them inside a bowl.
Add the butter, the nutmeg, the parmesan, 3 eggs yolks and 2 eggs white, whipped.
Mix all the ingredients until uniform. This "dough" will be your base and your top layer.
Take a baking dish, cover it with baking paper and spread the first layer.
For the filling
Add the slices of smoked scamorza.
Add the slices of soppressa.
Finish with the cubes of Asiago.
Top the filling with the remaining potato dough.
For the topping
Sprinkle 4 tablespoons of breadcrumbs on top and bake it at 350°F (180°C) for 30-40 minutes until the top is crusty and golden brown.
Notes
You can increase the number of eggs by 2 yolks, in case you would like a more firm consistency to the pie. I think that 3 eggs and 2 eggs white it is just perfect.
To whip the whites, I recommend starting whipping at the minimum speed and then increasing it little by little to the maximum. It will incorporate more air as the eggs are whipping, making them firm.
You can sub smoked scamorza with smoked mozzarella or provolone.
The soppressa, which is a typical regional product of the Veneto region, can be substituted with salami or cooked ham.
For the Asiago, also a region Venetian product, you can use instead mozzarella.